Queues vs Stacks: The FIFO & LIFO Showdown!

Picture this: you're standing in line at your favorite coffee shop. The first person who ordered gets their latte first. That's FIFO in action! Now imagine stacking plates - the last plate you put down is the first one you pick up. That's LIFO magic! Let's break down these super useful concepts.

Queues: First-In-First-Out (FIFO)

Queues work exactly like real-world lines. The first item that enters is the first to leave. Just like:

• People waiting for a bus
• Printing documents (first document sent prints first)
• Customer support tickets

# Python queue example
from collections import deque

queue = deque()
queue.append('Order #101')  # First in
queue.append('Order #102')
queue.append('Order #103')

print(queue.popleft())  # First out → Order #101

Stacks: Last-In-First-Out (LIFO)

Stacks behave like your browser's back button – your last visited page is the first one you return to. Other examples:

• Pancakes! (You eat the top one first)
• Undo/Redo functions in editors
• Backpacking items (last item packed is first accessible)

# Python stack example
stack = []
stack.append('Page 1')  # Browser history
stack.append('Page 2')
stack.append('Page 3')

print(stack.pop())  # Last in, first out → Page 3

Head-to-Head Comparison

When to Use Which?

Use Queues When:
• Handling requests in order
• Processing tasks sequentially
• Managing waitlists

Use Stacks When:
• Tracking previous states (like undo)
• Reversing order of items
• Implementing depth-first search

Pro Tips & Actionable Takeaways

1. Queues are perfect for fair ordering systems
2. Stacks excel at reversal and backtracking
3. In Python, use deque for queues (faster pops from left)
4. JavaScript arrays can act as both queues and stacks!

Whether you're coding or just organizing your desk, FIFO and LIFO principles are everywhere. Now go impress your friends by explaining why the undo button works like a stack of pancakes!